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Recent publications mention three species of shemayas is written from the Danube drainage: (1) Alburnus mento (Heckel, 1836); (2) Alburnus danubicus Antipa, 1909; (3) Alburnus sarmaticus Kottelat & Freyhof, 2007. The distribution of A. mento is restricted to the subalpine lakes of upper Danube-section, while A. danubicus and A. sarmaticus are two of the rare species of the lower, estuarine section of Danube, Dnepr and South-Bug. The distribution areas of the two latter species - at least - partly overlap. According to Freyhof and Kottelat A. danubicus extinct, and no specimen examined by Antipa or Drensky. There are historical data available in the literature on the Hungarian occurrence of Alburnus mento species group. Additionally the Hungarian Natural History Museum (HNHM) hosts some alcoholic preserved specimens, partly from the Caspian-sea, partly from the lower Danubian localities. Taxonomic status of shemayas should be reevaluated in light of the discovery of a museum specimen (HNHM 58.315.1) that was collected and identified by Antipa in 1935. In this paper I present the Hungarian distribution of shemayas, based on literature data. Additionally, I describe the examination of nine preserved specimens of HNHM, of which three, collected in the area of Caspian-sea basin, were identified as A. chalcoides. All the six specimens from the Danube drainage belong to A. danubicus. The specimen with catalogue number HNHM 58.315.1 can be designated as neotype of A. danubicus. In accordance with its meristic data I modified the diagnosis of the species. However it can be concluded that A. sarmaticus, described by Kottelat and Freyhof in 2007 is the synonym of Alburnus danubicus Antipa 1909. [ABSTRACT FROM AUTHOR]

Although ground-baiting related nutrient loading has been widely studied, we do not know what proportion of these nutrients release into the water column, affecting primary production directly. We conducted short-term (24-h, 5-day) experiments at wide temperature range, in presence and absence of fish using fish meal-based (FM-GB) and plant-based groundbait (PB-GB), to assess the nitrogen (N) and phosphorus (P) fluxes from GB into the water column. Nitrogen release from unconsumed FM-GB was negligible in the first 3 days, then increased abruptly, releasing 32% of its total N content by the fifth day. In contrast, PB-GB acted as temporary sink for inorganic N forms. Considerable (18-21%) inorganic P release was observed in both GB types in the first twelve hours. Consumed GBs induced considerable inorganic N release and its rate increased with temperature. Particulate forms predominated the released N in PB-GB, suggesting impaired digestion. Phosphorus-dominated by particulate forms-release was similar or lower than in unconsumed GB. Based on our results, excessive use of GB-when high amount of it remains unconsumed-can enhance eutrophication in P-limited ecosystems. Although less digestible GBs may have less abrupt effect on the primary production, undigested nutrients remain unavailable for removal through fish harvest., (© 2023. Springer Nature Limited.)

This paper presents geospatial datasets, figures, and tables illustrating i) the location and total area of fish farms under cultivation; and ii) the spatiotemporal dynamics of reed cover in Hungarian fishponds generated from the published study of Sharma et al., [1]. Preliminary data for fish farm locations were obtained from the Institute of Agricultural Economics (AKI), followed by significant refinement based on high-resolution Google Earth Pro-imagery. The fishpond area dataset was validated against the values reported in annual statistical reports on aquaculture. In order to map reed vegetation freely available Sentinel-2 imagery (between 2017 and 2021) was accessed from the Copernicus Open Access Hub [2] and emergent macrophyte cover was classified using the NDVI-based threshold values [1]. Scientists, policymakers, and fish farmers can all benefit from such geospatial datasets. It could be used to monitor the extent of fishponds in Hungary and to design farm-level reed management plans to optimize the provision of ecological and production services., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Author(s).)

Fish have somehow colonized isolated water bodies all over the world without human assistance. It has long been speculated that these colonization events are assisted by waterbirds, transporting fish eggs attached to their feet and feathers, yet empirical support for this is lacking. Recently, it was suggested that endozoochory (i.e., internal transport within the gut) might play a more important role, but only highly resistant diapause eggs of killifish have been found to survive passage through waterbird guts. Here, we performed a controlled feeding experiment, where developing eggs of two cosmopolitan, invasive cyprinids (common carp, Prussian carp) were fed to captive mallards. Live embryos of both species were retrieved from fresh feces and survived beyond hatching. Our study identifies an overlooked dispersal mechanism in fish, providing evidence for bird-mediated dispersal ability of soft-membraned eggs undergoing active development. Only 0.2% of ingested eggs survived gut passage, yet, given the abundance, diet, and movements of ducks in nature, our results have major implications for biodiversity conservation and invasion dynamics in freshwater ecosystems., Competing Interests: The authors declare no competing interest., (Copyright © 2020 the Author(s). Published by PNAS.)